1. Field of the Invention
The present invention relates to a radio communication system in which its operation is carried out by a digital frame, and more specifically to an address assigning system for the address field of a digital frame, which is based on the technical idea of the HDLC (high-level data link control procedure).
2. Description of the Related Art
In general, communications among a number of transmitting/receiving devices by radio are conducted in accordance with a protocol called the communication control procedure so that data communication between transmitting/receiving devices, in this case, a base station and a terminal device such as a radio transceiver, can be properly performed, To carry out transfer of data efficiently in accordance with this communication control procedure, a common transmission control procedure which is used among the transmitting/receiving devices should be determined in advance. Here, there have been proposed radio communication systems in which the technical idea of the high level data link control procedure (HDLC), one of the transmission control procedures, is employed.
U.S. Pat. No. 5,124,985 (Dec. 6, 1989) entitled "Radio Communication System using Time Division Digital Frame", is one of the prior art documents related to the radio communication system of the present invention.
The present radio communication system operates in accordance with the idea of the HDLC transmission procedure, and its frame structure is formed based on the technical idea of the HDLC. In the radio link through which data transmission is carried out by radio between a radio terminal device and a base station, when data is transmitted via a high-speed digital code, the frame length must be fixed so as to realize time division multi-channels and correct errors with error control codes. Further, in order to enhance the efficiency of transmission, it is required that a target field designed for data transmission should be enlarged as much as possible, and other fields should be reduced as small as possible. As a result, the number of bits used in the address field is very much limited. When the number of base stations and radio terminal devices increases more than the capacities in the address field, identification of base station and radio terminal devices cannot be carried out any longer.